Some embodiments relate generally to the field of biological treatments and the exploitation of organic waste.
More particularly, some embodiments relate to a process for the treatment of organic waste which couples in situ biostimulation to produce hydrolytic enzymes and hydrolysis of the refractory organic matter from waste using these enzymes with a view to energy recovery.
Hydrolysis corresponds to a step in solid-state fermentation which promotes the growth of different types of microorganisms, inter alia filamentous fungi, which produce extracellular hydrolyzing enzymes. The production of enzymes by solid-state fermentation is a process known to those skilled in the art and well documented in the scientific literature1,2,3.
Moreover, patents and patent applications describing the production of enzymes in solid medium are also found in the literature. More particularly, the Malaysian patent application MY142205, “Solid-state bioconversion of oil palm biomass by white rot fungus for ligninase production in rotary drum bioreactor” describes the use of Phanerochaete chrysosporium for producing ligninase. A substrate (or solid organic waste) is prepared (delignified) before solid-state fermentation and then the enzyme produced is collected. International application WO 2013/114282 (“Reduction of non-starch polysaccharides and alpha-galactosides in soy-flour by means of solid-state fermentation using cellulolytic bacteria isolated from different environments” describes a process for solid-state fermentation of soy flour in the solid state, in which cellulolytic bacteria are inoculated in the medium. Finally, international application WO 2013/162165 (“Method for producing large quantities of cellulase using palm by-products”) describes a process for solid-state fermentation using the fungus Aspergillus oryzea to produce cellulase.
The drawback of these processes of solid-state fermentation lies in the fact that the phase of preparing the solid matrix must allow for a very fine particle size, which is not possible in industrial installations. Other types of preparation of the matrix also involve chemical pretreatments for delignification or physical pretreatments such as sterilization and autoclaving. There is also the constraint of preparing the inoculum.
Moreover, it is known to those with ordinary skill in the art to use enzymes to degrade the organic matter. Thus, in the scientific literature a certain number of articles are found, describing processes of solid-state fermentation for producing different types of enzymes, which are extracted and used in tests of production of reducing sugars on various matrices (referred to as saccharification assays)4,5,6,7. Likewise, the Russian patent RU2238319 (“Complex enzyme preparation for hydrolysis of vegetable waste, among them food waste”) describes the use of enzymes (mixture of enzymes) to degrade the organic matter.
American patent U.S. Pat. No. 7,270,751 (“Method for treatment of sewage plant sludges by a fungal process”) and the American patent application US 2013/0040354 (“Biogas production process with enzyme pre-treatment”) and the international patent applications WO 2010/000858 (“A personal wash bar”) and WO 2013/163703 (“Integrated process for producing enzyme formulations from agro-industrial waste and biofuel production”) more specifically describe enzymatic hydrolysis and the degradation of organic matter:                U.S. Pat. No. 7,270,751 describes a process for treating municipal sludge by fungi, which comprises a step of oxidation, then a step of addition of antibiotics and of oxidizing compounds and finally a step of injection of a microfungus into the system to perform the treatment;        in US 2013/0040354 and WO 2010/000858, physical/chemical/biological pretreatments are used and followed by addition of external enzymes and finally by a fermentation step;        WO 2013/163703 describes the production of a specific enzyme formula by solid-state fermentation, which is then extracted and used for the production of bioethanol or other products of green chemistry.        